Capped 22 times since his try-scoring debut against Samoa in 2005, the 25-year-old will arrive at Welford Road this summer.
Tigers head coach Richard Cockerill said: “He is a quality player with a decent amount of Test experience behind him and he has benefited from a couple of seasons playing his club rugby in France.
“We’ve been looking for a player to fit into the back three since we knew that Johne Murphy would be returning to Ireland and we think Horacio Agulla can develop and improve even further in this environment.
“He is a skilful footballer and he has plenty to offer here.”
Agulla has already experienced playing at Welford Road, starting a game for Argentina against Tigers in February 2007 in a World Cup warm-up fixture for the Pumas.